FR2978983A1 - Method for regeneration of particle filter in exhaust line of e.g. diesel engine of full hybrid motor vehicle such as car, involves cutting off fuel injection in engine such that oxygen is fed into exhaust line and accordingly in filter - Google Patents

Abstract

The method involves providing a set of electrical motors (2, 3) selectively driven along with a differential reducer (7). An internal combustion engine (1) e.g. diesel engine, is driven by vacuum or by the set of electrical motors, where fuel injection is cut off in the engine such that oxygen is fed into an exhaust line and accordingly in a particle filter. Quantity of oxygen in the filter is determined and compared with a predetermined value. An independent claim is also included for a device for regeneration of a particle filter in an exhaust line of an internal combustion engine.

Description

The present invention relates to a method and a device for regenerating a particulate filter in the exhaust line of a hybrid engine. exhaust of a combustion engine of a hybrid vehicle. A particulate filter is an element commonly used to limit polluting emissions from a motor vehicle. Such a particulate filter retains the particles contained in the pollutant emissions of the engine of the motor vehicle, these particles may be in the form of soot. However, it is necessary to periodically reduce the amount of particles retained in the filter: this is done by a regeneration operation of the filter. Regeneration is a catalyzed reaction that burns the particles in the filter. The regeneration is performed at an exhaust gas temperature which is higher than the temperature in normal operation of the exhaust gas. The addition of oxygen to the particulate filter also facilitates the regeneration reaction. It is therefore necessary to trigger a regeneration by creating these specific conditions in the exhaust line of the engine gas engine gases upstream of the particulate filter. For a gasoline or diesel particulate filter, it is therefore necessary to burn the particles stored in the filter before obtaining a certain limit called MSL for Soil Mass Limit. From this limit, it can occur during the regeneration too much exothermic release which can damage the filter substrate and thus impact the filtration performance by aggravated heating of the particulate filter. Specific regeneration conditions may, on the one hand, in particular be obtained by performing a post-injection of fuel in the exhaust gas to increase their temperature and consequently the temperature in the particulate filter, this over a period of time determined to correspond to the removal of particles retained in the filter by combustion. On the other hand, it is also possible to increase the supply of oxidizer, in the form of oxygen, to the particulate filter in order to increase the regeneration reaction. The scarcity of oxygen output gasoline engine is the main difficulty to obtain regeneration conditions, since the engine operates in conditions of stoichiometric richness for the operation of the pollution control system, or over-richness. Only the conditions of foot lift phases make it possible to obtain oxygen upstream of the particulate filter. [0007] The other solutions for obtaining oxygen at the exhaust can be the regulation of richness in poor, the injection of air at the exhaust or IAE, the addition of a pipe connecting the downstream compressor and the downstream turbine. However, each of these listed solutions has disadvantages. [0008] The regulation of wealth in poor impacts the performance of the engine, including its performance as well as its depollution and engine stability. In addition, this solution can not be implemented during phases of over-richness for the protection of components. [000s] The exhaust air injection, consisting of blowing clean air using an electric pump, is suitable for the low-load phases. It is not possible to use it during the very busy engine phases, for example when driving on the motorway without modifying the pump used. The pipe connecting the downstream compressor and downstream turbine is expensive and difficult to implement. The problem of the regeneration of a particulate filter arises particularly in hybrid vehicles for a particulate filter disposed in the exhaust of their engine. Indeed, car manufacturers are increasingly developing hybrid vehicles, that is to say simultaneously comprising a heat engine and at least one engine other than thermal, frequently an electric motor. These hybrid vehicles have the reputation of being clean and it is therefore appropriate that the pollution of the exhaust of their engine is done with the best efficiency possible and in particular the regeneration of their particulate filter is particularly well controlled. In addition, a hybrid vehicle with the possibility of alternating operation of the engine and the engine other than thermal offers opportunities that can be advantageously exploited in the context of the regeneration of a particle filter loaded with polluting particles. US-A-6 195 985 proposes a process for reducing pollutant emissions based on the scanning of the cylinders and the catalytic converter. To achieve this, the heat engine continues to operate either autonomously or by being coupled to an external source.

Temporarily, in some cylinders, fuel injection is suppressed and only air passes into the cylinders. In this way, the accumulated pollutants are sent to the catalytic converter which remains at operating temperature and is rich in oxygen. However, this shipment is only before the thermal engine is shut down. It follows that this document neither describes nor suggests how the problem of the regeneration of a particle filter, whatever the mode of use of the heat engine, can be solved. Therefore, the problem underlying the invention is, for a hybrid vehicle, to use the possibilities offered by such a vehicle to perform a regeneration of the particulate filter present in the exhaust line of the engine thermal of said vehicle, this regeneration being then under optimal conditions. To achieve this objective, it is provided, according to the invention, a method of regenerating a particulate filter in the exhaust line of a combustion engine of a hybrid motor vehicle comprising a heat engine and the less an engine other than a thermal one, these two motors being able to drive selectively and / or in combination at least two steered wheels by a gear, characterized in that it comprises a step of driving the vacuum heat engine by the or a motor other than that thermal, fuel injection being cut in the engine, so that oxygen is sent into the exhaust line and accordingly in the particulate filter. The technical effect is to take advantage of a mode of propulsion other than thermal, especially electrical, to drive the hybrid engine of the combustion engine by cutting the injection of gasoline so that oxygen is sent in the line exhaust. The propulsion of the vehicle is little affected during the vacuum drive of the engine by the non-thermal engine and the regeneration of the particulate filter is done under optimal conditions. Thus, the possibility of alternating thermal engines and other than thermal, including electric, offered in a hybrid vehicle for its propulsion also improves the regeneration of the particulate filter. This therefore contributes to the depollution of the vehicle and therefore to increase its image of a clean motor vehicle. Advantageously, this electric propulsion also driving the engine is made consecutively to a thermal propulsion, for which there is provided a ballast of the engine, to increase the thermal exhaust gas and therefore the temperature of the filter to particles. This also contributes to obtaining a regeneration of the effective particle filter by increasing the temperature of the particulate filter. The method according to the invention may further optionally have any of the following characteristics: - the hybrid vehicle comprising at least two electric motors as engines other than thermal, the first electric motor provides training of the hybrid vehicle while the second electric motor drives the vacuum engine. - The filter regeneration step is triggered after determination by a motor control of a quantity of polluting particles in the particulate filter at least equal to a critical value, said motor control being able to determine the amount of oxygen in the filter. filter relative to a predetermined value, this amount of oxygen must be at least equal to said value during the initiation of the regeneration. the method comprises, at the end of the regeneration step, the step of permuting the propulsion of the hybrid vehicle in a normal operating mode adapted to the running conditions existing at the given moment, this permutation step taking place after determination by the motor control of a quantity of polluting particles in the particulate filter at most equal to a dump value representative of the emptying of the filter. prior to said step of driving the vacuum heat engine, the method comprises a thermal propulsion step with ballasting of the heat engine in order to increase the temperature of the exhaust gases in the exhaust line and consequently in the filter with particles. the step of ballasting the heat engine comprises a reduction of the ratio between the heat engine and the steered wheels of the hybrid vehicle. - When the non-thermal engine is at least one electric motor associated with a battery, the ballasting stage of the engine comprises a charging of the battery by the engine through the electric motor running as a generator. The invention also relates to a device for regenerating a particulate filter in the exhaust line of a combustion engine of a hybrid motor vehicle for the implementation of such a method, the hybrid vehicle comprising a heat engine and at least one engine other than heat, these two motors being able to drive selectively and / or in combination at least two steering wheels by a gear, characterized in that it comprises an engine control capable of initiating and interrupting the reaction of regeneration, said engine control having means for modifying the normal operation of the propulsion mode of the hybrid vehicle as a function of the quantity of oxygen present in the particulate filter, at least one oxygen sensor capable of evaluating the quantity of oxygen in the particulate filter as well as fuel injection cut-off means in the engine. Finally, the invention relates to a hybrid vehicle having a heat engine and at least one engine other than heat, the exhaust line of its engine comprising a particulate filter, characterized in that it comprises such a device. regeneration of a particulate filter or that the regeneration of its particulate filter is made in accordance with such a method. Advantageously, the hybrid vehicle has two electric motors as engines other than the engine in a series-parallel architecture. Other features, objects and advantages of the present invention will appear on reading the detailed description which follows and with reference to the accompanying drawings given by way of non-limiting examples and in which: - Figure 1 is a schematic representation of an architecture of a hybrid vehicle, this architecture being of the parallel series type and which can be used to facilitate a regeneration process of the filter according to the present invention by placing the heat engine in order to increase the temperature of the gases of exhaust and therefore the temperature of the particulate filter to be regenerated, - Figure 2 is a schematic representation of an architecture of a hybrid vehicle similar to that of Figure 1, this architecture can be used to facilitate a filter regeneration process according to the present invention by increasing the supply of oxygen to the particulate filter to be regenerated. In general, the present invention relates to a method and a device for the regeneration of a particulate filter in the exhaust line of a heat engine 1 of a hybrid vehicle. Engine

thermal 1 of the hybrid vehicle can be both a diesel engine that a gasoline engine, the exhaust line in general and particulate filter in particular then being adapted to said heat engine 1. [0027] The present invention also relates to any type hybrid vehicle, that is to say with a heat engine 1 and at least one engine 2, 3 other than thermal. In Figures 1 and 2, the non-thermal propulsion comprises two electric motors 2, 3. In Figures 1 and 2, there is shown a hybrid vehicle with a series-parallel architecture. Although this architecture is preferred for the implementation of the method and the regeneration device described below, the present invention is not limited to said architecture. A sufficient condition that must fulfill a hybrid vehicle architecture that can be used in the context of the present invention is to allow a drive of the vacuum heat engine by at least one engine other than thermal present in said vehicle, the engine other than that thermal then having sufficient power to be able to perform this training as well as training in propulsion other than thermal vehicle. This non-thermal engine is advantageously an electric motor associated with a power supply means sufficiently charged with electricity to enable such a drive. Thus, the hybrid vehicle can be a hybrid vehicle series, that is to say composed of a heat engine coupled to a generator that powers a motor other than thermal. It can also be a hybrid hybrid vehicle, that is to say with a thermal engine and a non-thermal engine mounted on the same axis with a transmission type CVT box (continuously variable transmission). Advantageously, the hybrid motor vehicle is of the complete type, which translation corresponds to the English term "full hybrid". In such a vehicle, it is possible to use the propulsion other than thermal only low power but also in addition to the engine when a large power is required, especially during acceleration or high rises. In such a vehicle, with an electric motor as a non-thermal engine, the heat engine usually operates at a slightly higher load than necessary and uses this surplus mechanical energy to recharge the vehicle battery. In what follows, reference will be made to at least one electric motor and preferably two electric motors 2, 3 to illustrate the engine other than thermal. This is not limiting. Figures 1 and 2 illustrate the principle of a hybrid vehicle architecture of the series-parallel type. Such an architecture comprises a heat engine 1, which can be diesel or gasoline as well as two electric motors 2 and 3, the heat engine 1 being connected to a fuel tank 5. The first electric motor 2 is said to be the main electric motor and is in direct contact with the transmission by reduction gears or by planetary gear train to the differential gearbox 7 of the drive gear train. The second motor 3 is said secondary electric motor acting alternator and current generator to recharge a battery 4. The second motor 3 is connected to the heat engine 1 by an epicyclic train 6. [0035] Multiple combinations of operation are possible for this parallel series hybrid architecture. In FIG. 1, for example, the heat engine 1 is effective via the epicyclic gear train 6 for the propulsion of the vehicle but also serves to recharge the battery 4 via the second motor 3. [0036] In FIG. for example, the first electric motor 2, powered by the battery 4, is used to propel the vehicle while the second electric motor 3, powered by the battery 4, is used to rotate the heat engine 1 empty. Other combinations are also possible but are not detailed as less advantageous for use during the regeneration of a particulate filter. In the exhaust line of the engine 1, there is provided at least one particulate filter. This particulate filter can be associated with a

catalyst, advantageously a three-way catalyst or trifunctional catalyst for a gasoline engine 1 or a preferably two-way oxidation catalyst and / or a reduction catalyst of the SCR type (for selective catalytic reduction) for a diesel engine 1. This is not limiting. It has previously been established that the high temperature in a particle filter as well as the oxygen supply are optimal conditions for the beginning of a regeneration of the particulate filter by combustion of the polluting particles stored in said filter. . According to the present invention, for the supply of oxygen to the particulate filter, there is provided a driving step by an electric motor 3 of the vacuum engine 1. This training is performed by cutting the fuel injection into said engine 1 so that oxygen is sent into the exhaust line. This will be shown later in FIG. 2. The method of regenerating a particulate filter in the exhaust line of a heat engine 1 of a hybrid vehicle comprises the following steps, steps that are not, however, all necessary for the implementation of the present invention. For the first step of the process, during operation of the heat engine 1 on a stabilized point at the end of a period for which the amount of polluting particles, including soot, stored in the particulate filter becomes critical, it is planned to initiate the regeneration of particulate filter soot. To do this, the device for implementing the method comprises an engine control, advantageously connected or included in the on-board diagnostic device of the hybrid vehicle or OBD, the engine control detecting a quantity of pollutant particles in the filter. particles at least equal to a critical value. For the second step of the process, it is advantageous to regulate the temperature prevailing in the particulate filter, this temperature must be high enough to initiate the regeneration reaction. This is advantageously achieved by weighing the heat engine 1 in order to increase the temperature of the exhaust gas and thus of the petrol particle filter. This second step is however not compulsory but only optional and advantageous. For example, in the case of a temperature in the line that is insufficient, that is to say generally less than 450-500 ° C., the step of weighting the heat engine 1 may include a reduction in the ratio between the heat engine. 1 and steering wheels of the hybrid vehicle. In combination or as an alternative to this reduction, as shown in Figure 1, it is also possible to ballast the heat engine 1 via the second electric motor 3, this for charging the battery 4. This increases the engine load and therefore the temperature in the exhaust line. Once the temperature of the particulate filter has been increased in a temperature range corresponding to that allowing an initiation of the regeneration reaction of the particulate filter, it is proceeded to the fourth stage of the process which concerns an increase of the amount of oxygen delivered to the filter. This is shown in Figure 2. In Figure 2, the second electric motor 3 drives the epicyclic train 6 the heat engine 1 whose fuel supply was previously cut, which constitutes a vacuum drive of the heat engine 1. The engine control is able to determine the amount of oxygen in the filter needed to initiate the regeneration of the particulate filter from a predetermined value, this amount of oxygen must be at least equal to said value when initiating regeneration. In this case, as the heat engine 1 runs empty, it is the first electric motor 2 which serves for the propulsion of the hybrid vehicle via the coupling between said electric motor 2 and the differential reducer 7 of the train. drive wheels. The driving action by the second electric motor 3 of the engine 1 vacuum with cutoff of the fuel injection sends fresh air, so oxygen, in the exhaust line. This is, however, conditioned by the fact that the battery 4 is sufficiently charged to propel the hybrid vehicle and drive the heat engine 1 to empty and that the first 2 and second 3 electric motors are powerful enough to propel the vehicle respectively. and driving the heat engine 1 to empty. This therefore advantageously has no effect on the propulsion of the vehicle since the first electric motor 2 can replace the heat engine 1. As soon as the regeneration of the polluting particles of the petrol particle filter is sufficient and complete, the fifth stage of the The method provides for switching to a conventional propulsion mode of operation, this in accordance with the existing driving conditions at the given time. Referring to Figures 1 and 2, the invention also relates to a device for regenerating a particulate filter in the exhaust line of a heat engine 1 of a hybrid motor vehicle for the implementation of the method previously described. The device comprises an engine control capable of initiating and interrupting the regeneration reaction, said engine control having means for modifying the normal operation of the propulsion mode of the hybrid vehicle depending on the amount of oxygen present in the filter. with particles. For the determination of the amount of oxygen contained in the particulate filter, the device comprises at least one oxygen sensor capable of evaluating the amount of oxygen in the particulate filter. The device also comprises fuel injection cut-off means in the heat engine 1. Advantageously, for controlling the weighting step of the heat engine 1 in order to increase the temperature in the exhaust line, the device comprises at least one temperature sensor disposed in the exhaust line to control whether the temperature of the particulate filter allows a regeneration of the filter. If necessary, the motor control of the regeneration device advantageously comprises means for controlling a reduction in the ratio between the heat engine 1 and the differential gear 7 connected to the steering wheels of the hybrid vehicle, these control means acting advantageously on the train epicyclic 6 placed between the heat engine and the differential gearbox 7. [0056] Still to ensure the ballasting of the heat engine 1, the control means can be replaced or associated with means for recharging the battery 4 by the heat engine 1, this recharging being done advantageously via the second electric motor 3 operating as a generator. The main advantages of the present invention are, in addition to the flexibility of the initiation of the regeneration of a particulate filter by influencing at least the oxygen supply to the particulate filter by the introduction of a mode of propulsion of the hybrid specific vehicle, to provide for the addition of any additional element on the engine of the hybrid vehicle. Indeed, the initiation of the regeneration is facilitated by a particular operation of the engines already present in the hybrid vehicle, this operation being controlled by control elements already present in the vehicle. Such a regeneration process does not increase the cost of the hybrid vehicle. Another advantage lies in the possibility of oxygen supply for many points of regime with respect to the engine load, which allows to initiate and / or control regeneration phases even under the conditions of the invention. more severe, especially during very slow traffic in the city and / or rapid motorway traffic. A final advantage lies in the ease of regeneration of the particulate filter with a dependability of this regeneration, which allows compliance with the emission standards. The present method and regeneration device are all the more relevant as new European standards on the emission of particulate pollutants will generalize the use of particulate filter for petrol engine models and therefore particularly for hybrid vehicles with a petrol engine. Such standards will generalize the use of particle filters for gasoline models and the need to find ways of initiating the regeneration of particle filters loaded with such particles will become urgent. This will be reinforced by the creation of zones in cities dedicated to low emissivity vehicles, which will increase the number of vehicles, especially hybrid vehicles using a particle filter. The adoption of a method and a device for the regeneration of a particle filter for a hybrid vehicle also has a marketing aspect, given the reinforcement of the ecological image of the hybrid vehicle manufacturer that She bring. The invention is not limited to the embodiment described and illustrated which has been given by way of example.

Claims (9)

REVENDICATIONS1. A method of regenerating a particulate filter in the exhaust line of a heat engine (1) of a hybrid motor vehicle comprising a heat engine (1) and at least one engine (2, 3) other than heat, these two motors (1, 2, 3) which can drive selectively and / or in combination at least two steered wheels by a gear (7), characterized in that it comprises a step of driving the heat engine (1) empty by the or a motor (2, 3) other than thermal, the fuel injection being cut in the heat engine (1), so that oxygen is sent into the exhaust line and accordingly in the filter to particles. 2. Method according to the preceding claim, wherein, the hybrid vehicle comprising at least two electric motors (2, 3) as engines other than thermal, the first electric motor (2) drives the hybrid vehicle while the second electric motor (3) drives the heat engine (1) vacuum. 3. Method according to any one of the preceding claims, wherein the regeneration step of the filter is triggered after determination by an engine control of a quantity of polluting particles in the particulate filter at least equal to a critical value, said engine control being able to determine the amount of oxygen in the filter relative to a predetermined value, this amount of oxygen must be at least equal to said value during the initiation of the regeneration. 4. Method according to the preceding claim, which comprises, at the end of the regeneration step, the step of permutation of the propulsion of the hybrid vehicle in a normal operating mode adapted to the running conditions existing at the given time, this permutation step takes place after determination by the engine control of a quantity of polluting particles in the particulate filter at most equal to a dump value representative of the emptying of the filter. 5. Method according to any one of the preceding claims, which process, prior to said step of driving the heat engine (1) to vacuum, comprises a thermal propulsion step with ballasting of the heat engine (1) to increase the temperature of the exhaust gas in the exhaust line and consequently in the particulate filter. 6. Method according to the preceding claim, wherein the ballasting step of the heat engine (1) comprises a reduction of the ratio between the engine (1) and the steered wheels of the hybrid vehicle. 7. Method according to any one of the two preceding claims, for which, when the motor (2, 3) other than thermal is at least one electric motor (3) associated with a battery (4), the step of ballasting the thermal engine (1) comprises recharging the battery (4) by the heat engine (1) via the electric motor (3) operating as a generator. 8. Device for regenerating a particulate filter in the exhaust line of a heat engine (1) of a hybrid motor vehicle for carrying out the method according to any one of the preceding claims, the hybrid vehicle comprising a heat engine (1) and at least one motor (2, 3) other than heat, these two motors (1, 2, 3) being able to drive selectively and / or in combination at least two steered wheels by a gear, characterized in it comprises an engine control capable of initiating and interrupting the regeneration reaction, said engine control having means for modifying the normal operation of the propulsion mode of the hybrid vehicle as a function of the quantity of oxygen present in the particulate filter at least one oxygen sensor capable of evaluating the quantity of oxygen in the particulate filter as well as fuel injection cut-off means in the heat engine (1). 9. Hybrid vehicle having a heat engine (1) and at least one engine (2, 3) other than thermal, the exhaust line of its heat engine (1) comprising a particulate filter, characterized in that it comprises a regeneration device of a particulate filter according to the preceding claim or that the regeneration of its particulate filter is made according to a method according to any one of claims 1 to 7. 10O.Vélule hybrid according to the preceding claim, which presents two electric motors (2, 3) as motors other than the heat engine (1) in a series-parallel architecture.